Method and means of anchoring an object in the ground



March 5, 1968 e. LAGERSTRM 3,371,494

METHOD AND MEANS OF ANCHORING AN OBJECT IN THE GROUND Filed Feb. 4. 19664 Sheets-Sheet 1 INVENTQR. GUNNAR LAGERETROM ATTGRHE"! March 5, 1968 e.LAGERSTRbM METHOD AND MEANS OF ANCHORING AN OBJECT IN THE GROUND 4Sheets-Sheet 2 Filed Feb. 4, 1966 INVENTOli. GUNNAR LAGERSTROM ATTORNEYMarch 5, 1968 G. LAGERSTRM METHOD AND MEANS OF ANCHORING AN OBJECT .[NTHE GROUND Filed Feb. 4, 1966 4 Sheets-Sheet 5 FIG. 5

FIG. 4

INVENTOR." GUNNAR LAGERSTROM ATTORNEY 4 Sheets-Sheet 4 INVENTORL GUNNARLAGERSTROM ATTORNEY -March 5, 1968 G. LAGERSTRM METHOD AND MEANS OFANCHORING AN OBJECT IN THE GROUND Filed Feb. 4, 1966 United StatesPatent C) 3,371,494 METHOD AND MEANS OF ANCHORING AN OBJECT IN THEGROUND Gunnar Lagerstriim, Ektorp, Sweden, assignor to Atlas CopcoAktiebolag, Nacka, Sweden, a corporation of Sweden Filed Feb. 4, 1966,Ser. No. 525,068 12 Claims. (CI. 61-39) ABSTRACT OF THE DISCLOSURE Amethod and apparatus which provides for the installation of tieanchoring and/or reinforcing rods in soil adjacent construction areassuch as building foundations which includes utilizing a rotative and/ orpercussive power feed to drive a drill rod string carrying a rod anchorinto the soil and capable of penetrating rock therein and a drill tubestring enclosing the drill rod string and having an outer diameter lessthan the rod anchor; with the combined drill rod string and drill tubestring providing means for injecting washing fluid to said anchor duringdrilling and means for injecting grouting into the drilled hole throughthe tube string and out the lower end thereof around the drill rodstring and anchor while simultaneously withdrawing the tube string fromthe drilled hole.

This invention relates to anchoring objects such as sheet piling,building foundations, high tension power masts, suspension bridges, orthe like, in the ground by means of tie rods or making reinforced pilesin the ground.

One object of the invention is to enable or make possible the insertionof heavy tie rods or reinforcing rods in the ground and the embeddingthereof in concrete or the like and anchoring the tie or reinforcingrods in soil of any kindor in bed rock covered by such soil. Theinvention is particularly suitable in connection with buildingfoundations where very heavy tie rods, capable of taking a tension loadof 50 or 100 tons or more, have to be securely anchored in the soil orin the bed rock without removing the overburden. The invention isparticularly advantageous in connection with the construction ofbuilding foundations where the walls around the excavated cavity for thefoundation are formed by sheet piling which has to be anchored by meansof tie rods against pressure from the outer side by earth masses and/oradjacent buildings. However, the invention may also be used for makingreinforced concrete piles capable of taking large loads.

According to this invention, there is provided for driving down a rodstring and a tube string enclosing said rod string through theoverburden soil to bed rock, it any, by means of a rock drill with apower feed, said rod string carrying a rod anchor with an externaldiameter in excess of the outer diameter of the tube string and capableof penetrating rock for a suitable distance and means for conveyingflushing medium to the bottom of the hole produced by the rod anchor,disconnecting the rod string from the rock drill, closing an end of thetube string adjacent the rock drill, injecting grouting or other soilstabilizing material under pressure through the tube string,successively withdrawing the tube string from'the ground while suchgrouting injection is going on preferably until the tube string iscompletely withdrawn from the hole, and

3,371,494 Patented Mar. 5, 1968 ICC connecting the rod string to theobject when the grouting or the like has settled. The invention alsoprovides the means for driving down and anchoring a rod string as wellas the rod string itself. In some instances, particularly in connectionwith the formation of piles, the tube string may be left in the groundto enclose the concrete or grouting which is injected therein.

The invention is described below and illustrated in the accompanyingdrawings which show two embodiments of means for carrying out theinvention in practice.

FIG. 1 is a diagrammatic view illustrating in vertical section a portionof an excavation for a building foundation surrounded by a wall of sheetpiling;

FIG. 2 illustrates the injection of grouting or concrete or other soilstabilizing material around a tie rod string;

FIGS. 3a and 3b illustrate on a larger scale a wall of sheet piling, adrill wagon and a drill used for driving down a tie rod string and atube string from a space dug out behind such wall;

FIG. 4 illustrates in longitudinal section and partial side view theupper end of a tie rod string and a tube string and connections to arock drill according to one embodiment of this invention;

FIG. 5 is a detail of the rock drill;

FIGS. 6a and 6b illustrate a tie rod string and a tube string of anotherembodiment of this invention;

FIG. 66 illustrates a portion of the equipment in FIG. 6a afterdisconnection of the tie rod string; and

FIG. 7 is a detail of the equipment in FIG. 4 used for closing the upperend of the tube string during injection of grouting or the like afterdisconnection of the tie rod string.

In FIGS. 1, 2, 3a and 3b, a cavity 1 is illustrated which provides spacefor a drill wagon and other equipment necessary in connection with theconstruction of a building foundation. The cavity 1 is surrounded bywalls of sheet piling 2, which may or may not have been driven all theway down to bed rock 3 and which may be formed as a continuous wall withopenings for the tie rod and tube string or the sheet piles may beplaced with a distance between them to permit the insertion of the tierod and tube strings in between the piles; The overburden, which extendsdown from the original ground level 4, may comprise loose soil, sand,boulders, filling material or the like. 5 indicates boulders or blocksin the overburden soil, 6. The cavity 1 is preferably excavated with asuitable digging machine while the tie rod anchoring goes on so that anupper row of tie rods is positioned before the cavity 1 is dug out toits final low level, 7.

The use of tie rods facilitates moving around of the various equipmentnecessary for excavating and for the work required for fitting the tierods. In FIGS. 1, 2, and 3, 8 indicates a drill wagon which isillustrated more diagrammatically in FIGS. 1 and 2 and more in detail inFIG. 3a and which is of a known type which provides a feed bar 9 whichmay be swung up or down relative to the substructure of the drill wagonand fixed in any desired angle with regard to the substructure by meansof telescopic supports 10.

This drill wagon is basically of substantially conventional design andis provided with a rock drill 11 which may be a hammer drill asillustrated or a rotary drill of any suitable type which drill may bemoved up and down the feed bar 9 by means of a chain 12 and a reversiblefeed motor 13. The rock drill may be of any heavy type, provided with apowerful rotation mechanism driven by a separate reversible rotationmotor 14 of suflicient power to rotate a large rod anchor and a tube.The drill wagon is furthermore provided with a winch 15 which has asteel Wire cable 16 running over a sheave 17 at the top end of the feedbar 9 and provided for pulling tubes or rods out of a hole in theground.

The illustrated equipment which is driven down into the ground consistsof a string of tie rod elements 18 which may be hollow or solid andwhich should have sulficient tensile strength to take up the heavytension applied to them when they are anchored in place an loaded. Thetie rod elements are screw threaded at both ends and are preferablyprovided with so-called rope threads fitting into coupling sleeves 20threaded in a corresponding way and preferably provided with axiallyextending wings 21. The uppermost tie rod element is screwed into asocket 22 of a shank adapter 23, FIG.

6a, which may be of conventional design for fitting into a drill chuck24 as in FIG. 5 with a portion having socalled Leyner wings or splines25 which may be inserted axially and then rotated through a small anglein the drill chuck 24 so as to be axially locked therein in aconventional manner. The shank adapter may be provided with a flushingfluid passage 26 communicating with a corresponding flushing fluidpassage 32 in the tie rod element 18. Flushing fluid may be suppliedthrough a hose 27 and a tube 28 (FIG. 3a) extending through the drilland communicating with the passage 26 in the shank adapter 23 inconventional manner. Optionally flushing fluid may be supplied to theshank adapter through a hose connection 29 and a swivel bushing 30communicating through passages 31 with the flushing fluid passage 26,FIG. 4.

Flushing fluid passing through the shank adapter may flow through thepassages 32 in the tie rod elements down to a tie rod anchor 33 throughpassages 34 in the tie rod anchor opening at the bottom of the hole. Thetie rod anchor 33 in this case has a number of wings 35 carryingradially extending inserts 36 preferably of tungsten carbide or othermaterial suitable for penetrating the type of rock in which the tie rodelements and anchor is going to be inserted. The tie rod anchor 33 isfurthermore provided with guiding wings 37 extending axially from thetie rod anchor and serving to guide the tie rod anchor in the lower openend of a string of tube elements 38. When a rotary drill is used the rodanchor may, of course, be of other design and in certain types of groundso-called tricone bits or similar types of rod anchors may be used.

The tube elements 38 are connected to form a string of tube elements bymeans of threaded couplings 39 which couplings are preferably providedwith so-called rope type threads fitting into similar threads 40 in theends of the tube elements 38. The couplings 39 are preferably providedwith a wrench grip 41 and similar wrench grips 42 are provided on therod elements in order to facilitate assembling and disassembling of thetie rod string or reinforcing rod string and the tube string. The wings21 on the rod couplings are of such dimensions that they can passaxially clear of the inner wall of the couplings 39. The uppermost tubeelement 38 is screwed to a sleeve 43 which has a radial flange 44 forfacilitating withdrawal of the tube string from the hole. In FIG. 6a thesleeve 43 is screwed to a flushing head 45 which flushing head isscrewed to the shank adapter 23 by means of screw threads 46 as alsoillustrated in FIG. 6c. The threaded portion on the head 45 is shorterthan the rope threaded portion 19 on the rod elements and has higherlead than the threads 19 in order to come apart easier than any of therod couplings. The flushing head 45 is surrounded by a swivel bushing 47provided with a hose connection 48 communicating with a flushing mediumpassage 57. The swivel bushing 47 is kept in place on the flushing head45 by means of a locking ring 49.

In the embodiment of FIG. 4 the sleeve 43 is not screw-threaded to theshank adapter 23, but instead a flushing head or bushing 50 is insertedin the sleeve 43 with a rotary and axially slidable fit so that thebushing 50 can be moved down until it rests with an annular flange 76 onthe flange 44 of sleeve 43. The flushing head 50 has a fluid connection52 for the supply of flushing fluid from a suitable source, said fluidconnection 52 communicating through a check valve 53 with a passage 51leading to a fluid passage 69 between the tie rod string and the tubestring. The shank adapter 23 in FIG. 4 has a flange 74 which through anannular bearing surface rests on the upper end of the bushing 50.

In order to pull out the tube string from the hole in the ground, aclamp 54 is provided. Said clamp 54 consists of two half ring partsprovided with ears 55 adapted to fit into rings 56 which through chainlinks 58 may be connected to hooks 77 on a slide 59 carrying the rockdrill 11 and guided along the feed bar and operated by the chain 16 andthe feed motor 13. Alternatively, the chain 58 may be connected to thecable 16 when it is desired to pull the tube string by means of thewinch 15. At the lower end of the feed bar 9, FIG. 30, two guidingclamps 60 and 61 are carried by the feed bar and adapted to hold thetube string during assembly operations and to guide it when the stringis driven down through the ground. The guide clamps may be tightened tohold the tube string in position when new tube elements are added or forother purposes, and they may also be left loose to guide the tube stringwhen the tube string and tie rod string is moved down into the ground,62 and 63 are air hoses for supplying compressed air to the rock drill11 and to the rotation motor mechanism 14, and 64 and 65 are hoses forsupplying flushing water or air to the tie rod string and the drill tubestring. Compressed air hoses for supplying compressed air to the feedmotor 13 and the winch 15 and the controls for said motors are notillustrated since they form no part of the invention and areconventional in drill wagons of the type illustrated.

When the tie rod string and anchor and the tube string have been moveddown and into bed rock, as illustrated in FIG. 3b, through the action ofthe rock drill and feed on the shank adapter 23, said adapter isunscrewed from the uppermost tie rod element 18 in FIG. 6a whereupon aplug 66, FIG. 60, is inserted in the shank adapter 23 to close theflushing passage 26. To carry out this operation the flushing head 45 isheld with a wrench engaging the grip 41. The drill is then rotated inreverse direction which removes shank adapter 23 from flushing head 45,whereupon the drill is retracted so that the tie rod element 18 isaccessible for removal from the shank. This retraction is possible dueto a clearance 79 between the rod anchor 33 and the lower end of thetube string 38. It may then be suitable but not always necessary toreplace the uppermost tie rod element 18 by a slightly longer tie rodelement 18a having conventional or trapezoid screw threaded arrangementat the upper end for taking a corresponding nut. The tube string is thenwithdrawn a short distance by means of the winch 15 and fixed bytightening the clamp 60. The shank adapter with the plug 66 in it is nowmoved down on the rod 18a which may be hammered down. The shank adapter23 and flushing head 45 are again connected and the clamp 60 may now beloosened. The connection 48 is disconnected from the flushing fluid hoseand instead connected to a grouting or concrete injection hose 67 whichsupplies grouting or the like from a pump 68. Injection and successivewithdrawal of tube string 38 can then commence and continue for thelength of the feed.

With the device according to FIGS. 6a, b and c operation is then asfollows: by means of the feed motor 13 the drill and the tube string isslowly retracted and at the same time grouting or the like is suppliedthrough the connection 48 to the passage 69 between the tube string andthe tie rod string, to the lower end of the tube string around the tierod anchor 33 and as the tube string is retracted grouting iscontinuously fed around the tie rod string and into Cavities in the rockand inthe soil so that a continuous body 70 of grouting or concrete isprovided :as indicated in FIGS. 1 and 2, which figures in their upperparts show various completely anchored tie rods.

With the equipment of FIG. 4 the operations are slightly differentinsofar that, after withdrawal of the shank adapter 23 from the flushinghead 50 and removal of the uppermost tie rod element 18 for instance bymeans of a pipe wrench inserted :between 74 and 76, the flushing head 50is removed together with sleeve 43, a hollow tie rod element 18a or asolid rod 18b is attached to the tie rod string and a cover 72 isprovided in the uppermost tube element 38, FIG. 7. The drill is advancedto be sure that the tie rod anchor is against the bottom of the hole.The grouting hose 67 is connected to hose connection 80 and the clamps54 are connected to the chains 56, 58 and hook 77 or cable 16. Injectionand retraction of tube string can then go on as above described.

The injection of concrete or grouting may be discontinned duringretraction of the tube string and it may be controlled so that thegrouting or concrete fills the cavities that may surround the tie rodstring. When the tube string has been withdrawn completely and as muchgrouting as desired has been injected, the injection hose, the tubestring and the drill wagon are moved away from the tie rod which is nowembedded as desired and extends a suitable distance through or from thesheet piling. The embedded tie rod assembly is left for as long asnecessary for the grouting to set. The projecting end of the tie rodstring is then provided with a suitable nut 71 and washer and tighteneddown on a horizontal channel or other member extending horizontallyalong the sheet piling as the case may be. Before the nut on the tie rodstring is completely tightened down the tie rod string may be tested inorder to check the tensile load which it can take. Such operations,however, are not described in further detail since they are conventionalin this art.

During the withdrawal of the tube string, it may be necessary, accordingto the length of the tube string, to disconnect one or more of the tubeelements, and during that operation the clamps 60, 61 are used to keepthe tube element which just comes out of the sheet piling in positionwhile other tube elements are removed and sleeve 43 and flushing head 45or the cover 72 are removed and afterwards fitted on the clamped tubeelement.

The above described method and means for producing the rod anchoringmeans may naturally be varied in many different ways according toprevailing conditions and objects which are to be anchored andparticularly according to the kind of soil and bed rock which isencountered in connection with operations of the above indicated type.The described method provides a convenient way of anchoring a tie rodstring and a tie rod anchor. Also, couplings between the tie rodelements are or may be well anchored within a body of concrete or thelike which, when it has set, forms a very efiicient anchoring means forsheet piling or other objects. The embodiments as above described shouldonly be considered as examples and may the varied in different wayswithin the following claims. Naturally, a tie rod string and a tubestring may under certain conditions comprise one single tie rod and onesingle tube of proper length. As mentioned above, the invention may alsoapply to the provision of more or less vertical rod strings which mayform the reinforcement of a pile of concrete or the like injected orcast in the tube string which may be left in the ground. I

1. The method of anchoring an object such as sheet piling, a buildingfoundation, a concrete pile, and the like in the ground by means of rodsand comprising the steps of driving a rod anchor and a rod string and anenclosing tube string substantially circular in cross section into theground and into bed rock if any exists by means of a rock drill withpower feed which feeds the rod string as well as the tube string, saidrod string carrying said rod anchor and said rod anchor having anexternal diameter in excess of the outer diameter of said tube stringand being adapted to penetrate rock and including means for conveyingflushing medium to the bottom of the hole produced by said rod anchor,disconnecting said rod string from said rock drill, closing an end ofsaid tube string adjacent said rock drill, injecting grouting underpressure through said tube string around said rod string for anchoringsaid rod anchor and said rod string in the ground, and, connecting saidrod string to said object when said grouting has set.

2. The method according to claim 1 which also includes the steps ofwithdrawing said tube string from the ground and from around said rodstring as said grouting is being injected.

3. The method according to claim 2 in which said grouting is injectedthrough the upper end of the said tube string and is expelled aroundsaid rod anchor and said rod string during a part only of saidwithdrawing of said tube string.

4. The method according to claim 1 in which said grouting is injectedthrough the upper end of said tube string and is expelled around saidrod anchor and said rod string while said tube string is left in theground.

5. The method according to claim 1 in which after disconnection of saidrod string from said drill an extra rod element is added to said rodstring, then pushing said rod string further to the bottom of the holeby means of said drill feed, and simultaneously pulling the tube stringup a short distance with a winch to assure that said rod anchor is atthe bottom of the hole when injection of grouting is started.

6. The method according to claim 1 in which an axial clearance isprovided between the lower end of said tube string and said rod anchorduring driving down of said anchor.

7. The method as described in claim 1 which includes the steps ofapplying both percussive and rotative force to said drill rod string andsaid drill tube string and in which said tie rod string includes aplurality of elements having means for transmitting said percussiveforce to said tie rod anchor, said elements being coupled together withtie rod couplings having means for anchoring in said grouting when set.

8. Apparatus for anchoring a rod string in the ground comprising thecombination of a drill wagon having a rock drill, a feed bar, reversiblemeans for moving said drill up and down said feed bar, a rod stringmeans for connecting said drill to one end of said rod string, a rodanchor at the opposite end of said rod string from said drill andadapted to penetrate rock for a short distance under the action of saiddrill, a string of tube substantially circular in cross-sectionenclosing said rod string and having an outer diameter less than theother diameter of said rod anchor, means for forcing said tube stringinto the ground following said rod anchor as said anchor penetrates intothe ground, means for closing the upper end of said tube string aftershort retraction of said tube string relative to said rod string, andmeans for injecting grouting through said closed end of said tube stringand to expel said grouting at the open opposite end of said tube string.

9. Apparatus according to claim 8 in which said rod anchor has guidingwings extending axially and in guiding cooperation with the inner wallof said tube string.

10. Apparatus according to claim 8 in which said rod i 7' ReferencesCited string comprises separate rod elements and rod couplings UNITEDSTATES PATENTS for connecting together said rod elements, said couplingsI having axially extending guiding means for forming an- 5x 2 1 choringmeans to be enclosed by said grouting and having 5 9 3 S16 en ausen 6 6a running clearance with respect to the inner walls of FOREIGN PATENTSW1 tube f 1,243359 8/1960 France.

'11. A tie rod string and anchor as recited 1n claim 8. 374 19 19 4Switzerland 12. The apparatus as set forth in claim 8 in which said rodstring is solid. g 10 JACOB SHAPIR-O, Primary Examiner.

